With the arrival of the Internet age, the quantity of smart mobile devices gradually increases. In various mobile devices, mobile phones are doubtlessly the most common and portable mobile terminal devices. Acoustic devices for playing audio are widely applied to smart mobile devices such as mobile phones.
A vibration system and a magnetic circuit system that are applied to an acoustic device directly affect the acoustic quality of the acoustic device. To improve stability of the vibration system, a vibration system of a micro acoustic device in the related art includes a first vibrating diaphragm fixed to a frame and used to vibrate and produce a sound, a second vibrating diaphragm used to improve transverse stability of a voice coil, and a flexible circuit board.
The second vibrating diaphragm is attached and fixed to the flexible circuit board, to form a combined flexible circuit board-vibrating diaphragm structure, used to connect to a voice coil lead wire to input an electrical signal, and avoid a problem that the voice coil lead wire breaks due to vibration of the vibration system especially in large power and large amplitude cases. The flexible circuit board includes two fixing arms respectively fixed to the frame and the voice coil and an elastic arm connecting the two fixing arms. The second vibrating diaphragm includes two fixing portions respectively fixed to the two fixing arms and a vibration portion connecting the two fixing portions. The voice coil lead wire of the voice coil is electrically connected to the flexible circuit board.
However, in the related art, a pad of the flexible circuit board that is used to electrically connect to the voice coil is located at a corner R outside the voice coil, and therefore, is located below the second vibrating diaphragm. When the second vibrating diaphragm vibrates, the pad is likely to hit the second vibrating diaphragm and generates noise. In addition, the pad occupies space of the elastic arm of the flexible circuit board. As a result, the elastic arm of the flexible circuit board becomes shorter, and has a breaking risk during vibration, thereby affecting the acoustic performance and the reliability of the acoustic unit.
Therefore, it is necessary to provide a new acoustic device to resolve the foregoing technical problem.